Precision Rifle Project Series: Savage 10FP Part 5

It has been about six weeks since I posted a very significant update to the Savage 10FP Precision Rifle Project Series, which consisted of the acquisition and install of the Vortex Optics Razor HD AMG 6-24x50mm EBR-7 MRAD, as well as load development with Lapua 6.5 Creedmoor brass.

At the time I settled on a nice ~1/2 MOA load consisting of:

Berger Bullets 6.5mm 140gr Hybrid Target

42.0gr Hodgdon H4350

CCI BR4 or Wolf Small Rifle Magnum

Lapua brass

This load is pushing around 2750fps in my 24″ 1:8″ Shilen barrel and was performing relative consistently.

But I also bought a couple boxes of the Berger Bullets 6.5mm 130gr AR Hybrid OTM Tactical. This was initially designed to be more tolerant of a jump to the lands, and thus be more suited to magazine length (~2.800″) cartridge overall length loads.

I ended up doing a quick work up trying out the Berger 130gr AR Hybrid:

Berger Bullets 6.5mm 130gr AR Hybrid OTM Tactical

Hodgdon H4350 – 43.0gr and 43.5gr

Lapua brass

Wolf Small Rifle Magnum

Cartridge Overall Length (COL) ~ 2.830″

Note: The 6.5mm Creedmoor was originally designed to accommodate a 2.800″ COL (same as .308 Winchester) for magazine length compliance. SAAMI defines a minimum and maximum COL of 2.700″ and 2.825″ for 6.5mm Creedmoor respectively. Most AICS compatible magazines can accommodate at least 2.850″ COL. Checking the distance to lands with the Berger 130gr AR Hybrid in this gun, the cartridge base to ogive measured 2.242″. Measuring the base to ogive length of the loaded cartridges with the ~2.830″ COL showed 2.227″. So with the current round count of this barrel (390 rounds exactly), I am jumping the Berger 130gr AR Hybrid around .015″ or fifteen-thousandths of an inch.

The 10-shot test groups showed immediate results.

43.0gr H4350 pushed the Berger 130gr an average of 2872fps and 43.5gr H4350 pushed it an average of 2904fps.

I ended up deciding on further testing of 43.5gr H4350 with the Berger Bullets 130gr AR Hybrid and shot a 5-shot group under 1/2 MOA.

The 10-shot group with 43.0gr H4350 had an average muzzle velocity of 2776fps and actually had a decent group size of .654″ center to center. On the other hand, the 10-shot group with 43.5gr H4350 had an average muzzle velocity of 2913fps and a group size of .960″ center to center. 43.5gr H4350 in Hornady brass has the velocity I want, but not the accuracy.

I did acquire a Redding carbide neck bushing in .290″ diameter, so I have switched out to that for future resizings. I will try messing around with Hornady brass and the Berger 130gr, again. I think I can get this brass to shoot well in this gun.

That being said, I have decided to utilize the Berger Bullets 6.5mm 130gr AR Hybrid OTM Tactical as my primary bullet for this particular Savage rifle. The Berger 140gr Hybrid Target does have a better G7 ballistic coefficient of .311, as opposed to the G7 BC of .287 for the Berger 130gr AR Hybrid OTM Tactical. But the key is that I can push the 130gr more than 150fps faster than the 140gr. This combined with the respectable .287 G7 BC makes for a flatter drop.

Berger 130gr AR Hybrid OTM Tactical vs Berger 140gr Hybrid Target

Drop Table in MILs. Assuming 2900fps for 130gr and 2750fps for the 140gr. 0ft elevation. Run through JBM Ballistics.

Range (Yards)

Berger 6.5mm 130gr
AR Hybrid OTM Tactical

Berger 6.5mm 140gr
Hybrid Target

100

0.0

0.0

200

-0.4

-0.4

300

-1.0

-1.1

400

-1.7

-1.9

500

-2.5

-2.8

600

-3.4

-3.7

700

-4.4

-4.8

800

-5.5

-5.9

900

-6.7

-7.2

1000

-8.0

-8.6

The above example shows a drop table comparison for the Berger 130gr AR Hybrid at 2900fps and the Berger 140gr Hybrid Target at 2750fps, at 0ft elevation / density altitude.

As you can see, the Berger 130gr AR Hybrid moving at 150fps faster than the Berger 140gr Hybrid Target will have less drop. While at known distance this is not much of a concern, it is helpful when you are shooting at unknown distances (on hit or miss targets). If your range estimation is off by +/- 25 yards, a flatter trajectory may save you by still getting a hit on target.

Granted, there is more wind drift with a lighter bullet at a certain point in the trajectory.

Wind table in MILs for a 10mph full value wind. Assuming 2900fps for 130gr and 2750fps for the 140gr. 0ft elevation. Run through JBM Ballistics.

Range (Yards)

Berger 6.5mm 130gr
AR Hybrid OTM Tactical

Berger 6.5mm 140gr
Hybrid Target

100

0.2

0.2

200

0.3

0.3

300

0.5

0.5

400

0.7

0.7

500

0.9

0.9

600

1.1

1.1

700

1.4

1.3

800

1.6

1.5

900

1.9

1.7

1000

2.2

1.9

The above is a wind drift table for the same bullets with the same data inputs as with the drop table (Berger 130gr AR Hybrid at 2900fps and the Berger 140gr Hybrid Target at 2750fps, at 0ft elevation / density altitude), but accounts for a 10mph full value wind.

As you can see, both the Berger 130gr AR Hybrid OTM Tactical and Berger 140gr Hybrid Target have the same amount of wind drift out to 600 yards. But at 700 yards, the Berger 130gr is starting to require more windage correction for the same 10mph wind as the the Berger 140gr. At the 1000 yard range, the Berger 130gr has 0.3 MILs of extra windage correction compared to the Berger 140gr.

To put that in perspective, 1 MIL at 1000 yards is 36 inches, or 3 feet. If the Berger 130gr has a wind drift of 2.2 MILs at 1000 yards for a 10mph wind, that means 1mph is 0.22 MIL of wind correction or 7.92 inches. If the Berger 140gr has a wind drift of 1.9 MILs at 1000 yards for a 10mph wind, that means 1mph is 0.19 of wind correction or 6.84 inches. This means you do have a slight wind advantage with the 140gr, however slight it appears after you do the math. But in a world where wind can be difficult to gauge, especially when wind never flows directly side to side between you and the target, or at constant speeds, every wind advantage can be valuable.

But in the end, I am willing to accept this wind drift difference and take the lighter, slightly lower G7 BC of the Berger 6.5mm 130gr AR Hybrid OTM Tactical as my primary bullet for this gun, simply because the muzzle velocity that can be achieved with the lighter bullet lets me get a slightly flatter trajectory (albeit with the small sacrifice of wind drift at the 700 yard mark and beyond).

That is pretty much the end of this rifle ‘project’ as it were. I do not intend to make any further changes to the gun in terms of parts. I plan on shooting this gun as is and when it starts to open up, we’ll see if I stick to 6.5mm Creedmoor for this rifle, or try something in a 6mm variant.

[…] am not entirely sure if I want to build another 6mm Creedmoor. Currently, my only 6.5mm Creedmoor is my rebarreled Savage 10FP, so building a 6.5mm Creedmoor rifle from the ground up is an option. I have always wanted to try […]